Thermostatic device



Oct. 30, 1928.

1,689,809 v. G. VAUGHAN THERMOSTATIC DEVICE Filed sept. :50, 1927 2sheets-sheet 1 F/ g /5Y 49 l 55 /6 6 /a /7 /7 s -Hf /3 E 'i z; I: V. /2/4 0 INVENTOR 7/ l//cf 6, Vaughan ATTRNEY v. G. VAUGHAN THERMOSTATICDEVICE Filed sept'. so, v1927- l 2 sheets-sheet 2 Y Hg. 5,

6 E@ i@ 66 l AT'TORNEY L heated device, and

Patented ct. 30, 1928.

UNITED STATES PATENT oFEicE.

-. VICTOR G. 'VAUG-HAN,v OF MANSFIELD, OHIO, ASSIGNOR T0 WESTINGHOUSEELECTRIC l MANUFACTURING COMPANY, A CORPORATION 0F PENNSYLVANIA.

. l THERMOSTATIC DEVICE.

Application led September 30, 1927. Serial No. 222,977:

vide a thermostatic control system for heated devices that shallregulate the length of time, during which a substantially constantquantity of heat energy is being developed, in accordance with thetemperature of the A further object of my invention is to provide athermostatic control systemthat shall be simple in construction,reliable in its operation and easily manufactured'and installed.

In practicing my4 invention, I provide a device to be heated, a heatingmeans therefor,

having a. substantially constant heat-generating capacity, a thermostatfor controlling the heating means, and means for controlling ,thefrequency of operation of the thermostat, whereby the temperature of thedevice to be heated may be varied over a relatively wide range oftemperatures.

For a fuller understanding of my invention, reference may be had to thefollowing description taken in conjunction withthe accompanyingdrawings, in which;

Figure l is a View in vertical section of an electrically heated,thermostatically-controlled flat iron,

' Fig. 2 is a view of a resistor element for controlling the frequencyof operation of a thermostat embodied in the device illustrated in Fig.1, n

Fig. 3 is a View of circuits and apparatus embodying my invention,

Fig. 4 is a top plan of a thermostatic switch embodied'in the deviceshownin Fig. 1,

Fig. 5 illustrates the temperature-time characteristics corresponding tothe various heatcontrolling positions of the switch illustratedschematically in Fig. 3,-

Fifr. 6 is a view illustrating schematically terial.

for a thermostatic switch embodied inthe device illustrated .in Fig. 1-whn the device is operated at its maximum temperature.

Fig.- 7 is a view illustrating schematically the circuit connections ofaresistor element and the heating element for the thermostatic switch,-whe'n the device illustrated in Fig. 1 is operated ata temperatureslightly lower than the vmaximum temperature. l

Fig. 8 is a schematic illustration of circuit connections of theresistor element of F ig.`2 and the-heating element for the thermostaticswitch embodied inthe device as shown in Fig. 1, when'theyiat iron isoperating at a medium temperature; and

Fig. 9 is a View illustrating the resistor element of Fig. 2disconnected from the heating element for the therniostatic switch whenthe device in Fig. 1 is operating at its minimum temperature.

In Fig. 1 of the drawings a flat iron, for tailoring purposes, isillustrated that comprises a sole plate 11, a weight casting 12 and a.cover 13 for enclosing theweight casting. The weight casting may besecured to the sole plate by studs 14 that haveI screw-thread engagementwith thesole plate. The cover may be provided witha handle 15 that issupported by astrap 16 of substantially U-shape. The

. the cover 13 and into the weight casting 12,

with which they have screw-thread engagement; i

`-"Ihe sole plate 11 is provided with an annularly-disposed' groove 21into which a heating resistor element 22 may be located. The

heating element may be insulated from the sole plate by insulation; 23of suitable ma- The temperature of the sole plate 11 may be controlledby a thermostatic switch 25 that is disposed in .anannular recess 26,located at the rear end of the sole plate 11.

The t-hermostatic switch 25 comprises a base 27 having a plurality ofspaced arcuate cona heating resistance element 37 attached to) the toface of the b-ase 27, the resistance ele-A tact members 28 to 32,inclusive, mounted on the bottom face thereof, a snap'v acting bi-.metallic disc 33 havin" 'a plurality of spaced contact bridging mem ers34, 35 and 36 attached thereto along the periphery thereof for bridgingthearcuate contact members, and

havingv Vportions that extend through the sheets 38, the base and thecontacts. in order:

to secure the heating unit and the` contacts securely against the base.The contact 31 may be secured to the base by means of a rivet and awasher 46. The terminals of the resistance element 37 may beelectrically connected to the terminals 42 and 43, thus 'connecting thecontacts 29 and l30 in series with each other.

The thermostatic disc 33 is preferably of the type disclosed in U. S.Patent No. 1,448,240l to J. A. Spencer, that is adapted to change itsshape abruptly when subjected to a' temperature of one value and toreturn abruptly to its Ainitial or normal shape when f subjected to atemperature of a different las ` is secured to one end of a stud bolt-47that value. Thus, the disc has two opposite limitingpositionsicorresponding to two different temperatures, the differencebetween which may be designated as the'temperaturediterentialof thedisc, which differential may be varied between relatively wide limits,depending upon the material constituting the disc and the method used inthe manufacturev In order that the contact-bridging mem- .bers 34, 35and `36 may cooperate with the stationaryfcontacts 28 to 32, inclusive,the disc has .screw-thread engagement with the base 27. means of thestud bolt,j the pressure betweenfthebridging vcontact members and thearcuate contactY memberscooperating therewith, when the thermostaticswitch 25 is in its circuit-closingposition, may be varied i or'adjusted ma predetermined value.

The electrical connection betweenthe .re-

' -s istance element 22 andthe switch 25 is shown schematically in Fig.4 of the drawings. One

lend of the resistance element 22 is connected 7 .toi-a terminal 48 thatis insulatedly mounted on .a .terminal supporting member 49, and theother end thereof is connected to the ter- Y minal 39 of the switch 25lThe terminal 41 l' of the switch 25 is connected to a terminal 52insulatedly mounted on theterminal supportingpmember 49.` The terminals48 and 52 may Abe connected to a source of electromotive force byconductors 53 and 54 that ma be located within a flexible conduit 55(see ig. 1). y

In order that the tem erature of the sole `plate 11 maybe varie .betweenpredetercommon terminal 61. The common terminal may be connected to aterminal 63 of the switch 59 and the termnals64 and 65 of the elements57 and 58 may be connected to terminals 67 and 68, respectively, of theselector switch 59. The terminal 42 of the thermostatic-switch 25 isconnected to the switch terminal 68 by a conductor 69, and the terminal43 is connected to a terminal 71 of the switch 59 by a conductor 72.

When a handle 74 of the switch 59 is moved successively toposit-ions 75to 7 8, inclusive, the heat-generating capacit of the heating element 37is so varied that tiie sole plate may be,.controlled at four averagetemperatures of predetermined values. Thus, when the `handle 74 is inthe position 75, the sole plate is controlled at a maximum averagetemperature, in position 76 at a lower temperature, in position 77 at astill lower temperature, and in the position 78 at a minimumtemperature.

The circuit connect-ions of the resistance elements 57. and 58, and theheating element 37 are shownpin Figs. 6` to 9, inclusive, for thevarious heat'controlling positions 75 to 78, inclusive, -of the switch59. In Fig. 6 the circuit -connection is illustrated when the switchhandle is in the position 75. In this position the heating element 37 isshort-circuited by a switch blade 81 that connects the terminals 67 and71 of the switch 59, and the ,temperatlie of the sole plate is regulatedat feet reenergization of the heating element 22.

If the handle 74 of the switch is moved to the position 76, the switchconnects resistance element 57 in parallel with the heating element 37,terminals 71 and 63 being connected together. Thus, the rate oi heatingof the switch 25 is so increased that the frequency of operation israised,gtherebv causing the resistance element 22 in the sole plate 11to be energized for a shorter period of time. Since llD fil.,

' constant; therefore, the sole pla-te is caused to be controlled at anaverage temperature represented by a line 86 of Fig. 5. Curve 87 of Fig.represents graphically the rate ofV `heating and cooling the switch whenthe handle 74 of the switch 59 is in thetemperature controllin position76.

If the switc handle .74 is moved to the position 77, the resistanceelements 57 and 58 `are connected in series witheach other and inparallel circuit relation to the heatinglele- .ment 37 ofthe switch 25.Thus, more current is caused to fiow through the element 37 than ineither of the switch positions 76 and 75, and the rate of heating theswitch 25 and the frequenc of operation thereof are increased stillurther, thereby causing the sole plate to be controlled at an averagetemperature/ represented by a curve 88. lie rate of heatin the switch 25for this temperaturecontro ling position is represented graphically by acurve 89.

If the' switch handle 74 is moved to the temperature-controllingposition 78, the resistance elements 57 and 58 are disconnected from theheating element 37, thereby connecting the element 37 directly inserieswith the heating element 22 in, the sole.I plate l1. With thiscircuit connection, the heating element 37 is enerating heat at itsmaximum capacity and n t e frequency of operation of the switch 25increased still further as shownby a curve 91 of Fig. 5. Thetemperature'of the sole plate corresponding to this heatinor positionmay bei represented by aline 92 of:v the same' ligure.'

The range of .temperatures over which the Asole plate is controlled,mayj be varied between relatively wide limits, by making theheat-generating capacity of the velement 37 quite large and thenprovidin means similar to the switch 59 and the resistance elements 57and 58 for varying or controlling the yamount of current traversing theele-l ment 37. Generally stated the greater the rate of heating of thethermostatic switch 25, the greater w11 be the frequency of operationthereof; t e greater the frequency of operation, the lower will be thetemperature at trolled.

which the sole plate 11 is controlled and the lower the frequency ofoperation of the thermostatic switch 25, that is, by decreasing therateof heating thereof, the higher will be the temperature Variousmodifications may be .made in the "device embodying my invention withoutdeparting from `the spirit and the scope thereof.. I desire at whch thesole plate is conlfor controlling the energy input to said 'heatingelement whereby the frequency of operation of said switch may be variedin accordance with a thermal conditionof a predetermined value to becontrolled by said switch.

2. In a heating system, a primary source of'heat, thermostatic 'meansresponsive thereto for controlling said source, and means forcontrolling the frequency of operation of said switch whereby thetemperature affected by said source may be selectively controlled.

3. lIn a heating system, a primary sourceof heat, thermostatic meansresponsive. to Va thermal condition affected thereby for controll-inoPsaid sources, an auxiliary source of heat fer heating said thermostatic`means, and means for controlling said. auxiliary source of heat. I

4. In a heating system, a primary source of heat, a. thermostatic devicefor controlling said vprimar source, in accordance with a thermal conition to be affected thereby, an auxiliary source of heat controlled bysaid switch for heating said switch, and means for controlling theenergy of said auxiliary source of lieat, whereby the 'frequency ofoperation of said thermostatic device is controlled.

5. In a heating system, the combination with -a device to be heated, aprimary heating element for heating the device, a thermostatic switchoperable when said device has been heated to one temperature todeenergize lsaid heating element and at another temperature to energizesaid element, an auxiliary heating element for heating the switch andmeansfor passing an electric current VAtherethrough, of means forcontrolling the heat generated by the auxiliary heating elementcomprising a ments connected to t e auxiliary heating element and aselector switch forvarying the `circuit connections between theauxiliary heatinor element andthe resistors whereby the rate of?1heating of said switch by said auxiliary heatingv element Fmay becontrolled.

lurality of resistor ele lll) 6. The combination with a thermostat, an

electric circuit controlled thereby in accordance with a .thermalcondition to becontrolled and a heating'element disposed in ,thermalvrelation to said thermostat and controlled thereby, of means forcontrolling the value 'of current traversing the heating elementcomprising a pluralit of resistor elements and a selector switch orvarying the circuit connections of said resistor elements to saidheating element.

an electric circuit controlled thereby 1n accordance with a thermalcondition to be con. trolled and a heating element connected in series'with said switch and disposed in thermal relation therewith, f means forvarying the current flowing through the heating element between zero anda predetermined value, whereby the frequency of operation of said'switch may be controlled, said 10 means comprising a. plurality ofresistor elements, and a selector switch for varying the amount of saidresistance elements connected in shunt with said heating element.

In testimony whereof', I have hereunto 15 subscribedmy name this 21 dayof Sept., 1927.

ViCToR` G. VAUGHAN.

